Monitor Device and Trolley Type Vehicle

ABSTRACT

A monitor device is provided with an imaging device that shoots an overhead line and a current collector, and a controller that processes an image. The controller includes a day or night determination processing section, and an image processing section that switches a parameter for recognizing the overhead line and the current collector in the image by executing image processing different in the daylight and at night based upon the result of the day or night determination. Further, there are provided reference photographic subjects to be shot by the imaging device in positions different from the overhead line and the current collector in an image area to be shot, and the day or night determination processing section performs the determination of day or night based upon a luminance average value of the reference photographic subjects inputted into an image input section.

TECHNICAL FIELD

The present invention relates to a monitor device that recognizes anobject from an image shot by an imaging device for image processing tomonitor the object and a trolley type vehicle with the monitor device.

BACKGROUND ART

A monitor device used in the form of being mounted on a vehicle outdoorsor the like is provided with an imaging device that shoots an object,and a controller that processes an image shot by the imaging device. Thecontroller includes an image input section that receives input of theimage shot by the imaging device, a day or night determinationprocessing section that determines day or night of the image inputtedinto the image input section, and an image processing section thatswitches an image processing parameter for easily recognizing the objectin the image by executing image processing different in the daylight andat night respectively based upon the result of the day or nightdetermination determined by the day or night determination processingsection. In this case, the day or night determination processing sectionperforms the determination of day or night based upon a luminance levelin the image shot by the imaging device to determine an imagingcondition (for example, refer to Patent Document 1). In addition, thereis described a trolley type transportation vehicle that mounts animaging device thereon and detects a relative position between apantograph and an overhead line (for example, refer to Patent Document2).

PRIOR ART DOCUMENT Patent Document

Patent Document 1: U.S. Pat. No. 8,204,305 B2

Patent Document 2: U.S. Pat. No. 9,022,153 B2

SUMMARY OF THE INVENTION

The aforementioned imaging device is provided with a camera with animaging element generally pixelated with a semiconductor such as a CCD(Charge Coupled Device). An image signal in accordance with light anddark (a luminance level) of light inputted into a camera light-receivingpart is outputted, but in an excessive light quantity, a so-calledhalation defect that an output signal is saturated is generated becauseof the characteristic of the imaging element, and in reverse, in a weaklight quantity, a so-called black defect that an output signal is toosmall to determine a photographic subject tends to be easily generated.Therefore, almost all of cameras to be sold on the market have an AGC(Automatic Gain Control) circuit in advance housed therein, the AGCcircuit outputting an image signal the luminance intensity (the width oflight and dark) of which is adjusted within a constant range byincreasing a gain when the light quantity is weak and decreasing thegain when the light quantity is excessive.

In a case where the aforementioned monitor device in the conventionaltechnology is mounted on a vehicle (a mobile object) such as a dumptruck, since the surrounding environment (the imaging environment)changes by such as not only a change in the weather or an elapse in timebut also transfer from a flat ground to a valley side by travel of avehicle, or reflection of street lamps at night, an luminance averagevalue in a specific area in the shooting image largely varies. Followingit, the AGC circuit automatically adjusts the luminance level in anentire image within a constant range, and therefore, in fact, thedetermination accuracy in the day or night determination possiblydeteriorates.

In order to overcome this problem, in Patent Document 1 as describedabove a sky area and a ground area are in advance set in the image, andday or night is determined based upon a ratio in the pixel numbershowing a predetermined luminance value in each of the areas. However,in the trolley type transportation vehicle as disclosed in PatentDocument 2, a monitoring object is the pantograph and therefore, it isimpossible to set the ground area within the shooting image.

The present invention is made in view of the aforementioned problems inthe conventional technology, and an object of the present invention isto provide a monitor device mounted on a trolley type vehicle thatimproves the determination accuracy in day or night determination of animaging environment therein.

In order to solve the aforementioned problems, a monitor deviceaccording to the present invention includes: an imaging device that ismounted on a vehicle and shoots an object outside of the vehicle; acontroller that processes an image shot by the imaging device; and aplurality of reference photographic subjects that are disposed to befixed integrally with the imaging device and are shot by the imagingdevice in positions different from the object in an image area to beshot, characterized in that: wherein the controller includes: a day ornight determination processing section that determines day or night inan imaging environment of the object; and an image processing sectionthat switches an image processing parameter for recognizing the objectin the image by executing image processing different in the daylight andat night based upon the result of the day or night determinationdetermined by the day or night determination processing section, whereinthe day or night determination processing section in the controllerperforms the determination of day or night based upon luminanceinformation of the plurality of reference photographic subjects, and theimage processing section in the controller executes the image processingusing the image processing parameter different in the daylight and atnight based upon the result of the day or night determination of the dayor night determination processing section.

According to the present invention, it is possible to improve thedetermination accuracy in the day or night determination on the imagingenvironment to be performed in the monitor device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a trolley type dump truck on which amonitor device is mounted according to a first embodiment of the presentinvention.

FIG. 2 is a partially enlarged front view showing a bracket, an imagingdevice and the like in FIG. 1.

FIG. 3 is a perspective view showing the bracket, the imaging deviceprovided with an illumination device, a left reference photographicsubject, a right reference photographic subject and the like.

FIG. 4 is a control block diagram of a controller.

FIG. 5 is a flow chart showing control processing of an initial settingto be carried out in the controller.

FIG. 6 is a flow chart showing processing for determining any one of adaylight mode and a night mode to be executed in the controller.

FIG. 7 is a flow chart showing processing of a day or nightdetermination in a daylight mode according to the first embodiment ofthe present invention.

FIG. 8 is a flow chart showing processing of a day or nightdetermination on a night mode according to the first embodiment of thepresent invention.

FIG. 9 is a flow chart showing image processing in accordance with theresult of the day or night determination.

FIG. 10 is an explanatory diagram showing a day image of daylightshooting inputted into an image input section, and a white and blackimage for daylight mode to which image white and black binarizationprocessing is executed in a binarization processing section in FIG. 4.

FIG. 11 is an explanatory diagram showing a night image of nightshooting inputted into the image input section, a white and black imagefor night mode to which the image white and black binarizationprocessing is executed in the binarization processing section and animage (the white and black image for day mode) to which white and blackinversion processing is executed in an inversion processing section inFIG. 4.

FIG. 12 is a front view showing an image in the daylight to be displayedin a display device.

FIG. 13 is a front view showing an image at night to be displayed in thedisplay device.

FIG. 14 is a flow chart showing processing of a day or nightdetermination in a daylight mode according to a second embodiment of thepresent invention.

FIG. 15 is a flow chart showing processing of a day or nightdetermination in a night mode according to the second embodiment of thepresent invention.

FIG. 16 is a control block diagram of a controller according to a thirdembodiment of the present invention.

FIG. 17 is a flow chart showing processing for determining any one of adaylight mode and a night mode based upon lighting and extinction of anillumination device.

FIG. 18 is a perspective view showing a bracket, an imaging deviceprovided with an illumination device, a left reference photographicsubject, a right reference photographic subject and the like accordingto a first modification example of the present invention.

FIG. 19 is a perspective view showing a bracket, an imaging deviceprovided with an illumination device, a left reference photographicsubject, a right reference photographic subject and the like accordingto a second modification example of the present invention.

FIG. 20 is a perspective view showing a bracket, an imaging deviceprovided with an illumination device, an upper reference photographicsubject, a lower reference photographic subject and the like accordingto a third modification example of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an explanation will be made of a monitor device accordingto embodiments of the present invention with reference to theaccompanying drawings by taking a case of being mounted on a trolleytype dump truck as an example.

FIG. 1 to FIG. 13 show a first embodiment of the present invention. Anoverhead line 1 (a trolley line) as shown in FIG. 1 is stretched on atravel path (a traffic line) of a mine, for example, to supply power toa dump truck 2 as a large-sized transportation vehicle that is used fora transportation work of minerals and the like excavated in the mine.The dump truck 2 is configured to include a vehicle body 3 having leftand right front wheels 4 and left and right rear wheels 5 driving by thepower from the overhead line 1, and a loading platform 7 disposed on abackward upper part of the vehicle body 3 to be rotatable (capable oftilting) in a upper-lower direction by a hoist cylinder 6.

The vehicle body 3 is provided with a cab 8 that is positioned on thefront side of the loading platform 7 and defines therein an operator'sroom in which an operator gets. An after-mentioned display device 39 isattached on the front side of an operator's seat in the cab 8. Anafter-mentioned controller 26 is disposed in the cab 8 to control(process) an image shot in an imaging device 21, which will be describedherein after.

A pantograph 9 is attached on a top surface of a mount 3A disposed onthe front side of the vehicle body 3. The pantograph 9 is disposed to becapable of moving up and down between the overhead line 1 and the mount3A facing to each other and is provided with a current collector 10 onthe upper end that makes sliding contact with the overhead line 1 totake in power. The dump truck 2 can drive a traveling motor (not shown)of the rear wheels 5 as drive wheels, for example, with supply of thepower via the current collector 10 from the overhead line 1.

Next, an explanation will be made of a monitor device 11 mounted on thedump truck 2.

The monitor device 11 monitors a contact (sliding contact) state betweenthe overhead line 1 and the current collector 10. That is, the monitordevice 11 monitors a positional relation between the overhead line 1 andthe current collector 10 such that the current collector 10 does notderail from the overhead line 1 at the traveling of the dump truck 2. Inaddition, the monitor device 11 is configured to include a bracket 12 onwhich the imaging device 21 is attached, the imaging device 21 thatshoots the overhead line 1 and the current collector 10, referencephotographic subjects 24 that are shot by the imaging device 21 inpositions different from the overhead line 1 and the current collector10 in an image area to be shot, and a controller 26 that processes animage that is shot by the imaging device 21.

The bracket 12 is disposed on the mount 3A of the vehicle body 3 to bepositioned on the back side of the pantograph 9. As shown in FIG. 2, thebracket 12 is configured to include a base tool 13 that is fixed on thetop surface side of the mount 3A by bolts (not shown), an intermediateattachment tool 14 that is fixed on the top surface of the base tool 13by bolts or the like and on which a portion of an after-mentioned cable22 along the path is attached, and an imaging device attachment tool 15that is fixed on the top surface of the intermediate attachment tool 14by bolts 16 and on which the after-mentioned imaging device 21 isattached.

A shown in FIG. 3, the imaging device attachment tool 15 is configuredof a seat 17 attached on the top surface of the intermediate attachmenttool 14, angle adjustment plates 18 that extend toward the forward sidefrom the upper end side of the seat 17 and an angle of which isadjustable to the seat 17, and an extension plate 19 that is fixed tothe tip end sides of the angle adjustment plates 18 by welding or thelike and extends in a left-right direction.

The seat 17 is configured of an attachment plate part 17A attached onthe top surface of the intermediate attachment tool 14, and verticalplate parts 17B rising up toward the upward side from both of left andright ends of the attachment plate part 17A. Two bolt through holes 17A1into which the bolts 16 are inserted are formed in the attachment platepart 17A as to be spaced in the left-right direction. The imaging deviceattachment tool 15 is attached to the intermediate attachment tool 14 byscrewing the bolts 16 into screw holes of the intermediate attachmenttool 14 through the bolt through holes 17A1. Two screw seats 17B1 arerespectively disposed on the inner surface side of each of the verticalplate parts 17B as to be spaced in an upper-lower direction.

Bolt through holes 18A (shown in FIG. 2 only) are formed respectively inpositions corresponding to the screw seats 17B1 of each of the verticalplate parts 17B on each of the angle adjustment plates 18. As a result,the angle adjustment plate 18 is attached on each of the vertical plateparts 17B by causing each of the bolts 20 to be inserted in each of thebolt through holes 18A to be screwed into each of the screw seats 17B1.In this case, as shown in FIG. 2, the bolt through hole 18A positionedon the upper side of the upper and lower bolt through holes 18A isformed in a curved long hole. Accordingly, the angle adjustment plate 18can adjust an angle thereof to the attachment plate part 17A on a basisof the bolt 20 positioned on the lower side.

The extension plate 19 is fixed to the tip end side of each of the angleadjustment plates 18 by welding or the like and extends in theleft-right direction. The extension plate 19 is configured to includesan imaging device fixing part 19A that is positioned between the leftangle adjustment plate 18 and the right angle adjustment plate 18 and onwhich the after-mentioned imaging device 21 is fixed, a left referencephotographic subject fixing part 19B that projects closer to the leftside than the left angle adjustment plate 18 and on which anafter-mentioned left reference photographic subject 24A is fixedtogether with the imaging device 21, and a right reference photographicsubject fixing part 19C that projects closer to the right side than theright angle adjustment plate 18 and on which an after-mentioned rightreference photographic subject 24B is fixed together with the imagingdevice 21.

A screw seat 19B1 is disposed on the rear surface of the left referencephotographic subject fixing part 19B to attach the after-mentioned leftreference photographic subject 24A thereto. Meanwhile, a screw seat 19C1is disposed on the rear surface of the right reference photographicsubject fixing part 19C to attach the after-mentioned right referencephotographic subject 24B thereto. Positions of the screw seat 19B1 andthe screw seat 19C1 are set such that the left reference photographicsubject 24A and the right reference photographic subject 24B enter intoboth of left and right end sides in an image shot by a camera 21B in theimaging device 21 to be described later.

Next, an explanation will be made of the imaging device 21 attached tothe imaging device attachment tool 15.

The imaging device 21 is mounted on the dump truck 2 (the vehicle). Theimaging device 21 is fixed on the extension plate 19 to be positionedbetween the left and right angle adjustment plates 18 of the imagingdevice attachment tool 15. The imaging device 21 is configured toinclude a casing 21A that is fixed to the imaging device fixing part 19Aof the extension plate 19, and the camera 21B that is disposed (housed)in the casing 21A. The camera 21B can shoot a shooting image by color,for example, and mounts thereon an AGC (Automatic Gain Control) circuitfor automatically adjusting a gain in accordance with an image to beshot. That is, the camera 21B automatically adjusts the gain inaccordance with the image to be shot.

As shown in FIG. 1, the camera 21B can accommodate the overhead line 1and the current collector 10 within a shooting range H by moving each ofthe angle adjustment plates 18 in the upper-lower direction. That is,the overhead line 1 and the current collector 10 are arranged outside ofthe dump truck 2 (the vehicle) and configure objects, which are shot bythe camera 21B in the imaging device 21, of the present invention. Thecamera 21B is connected to the after-mentioned controller 26 by thecable 22, and outputs the shot image toward the controller 26.

In addition, four illumination devices 23 are housed in the casing 21Aaround the camera 21B. The illumination devices 23 illuminate theoverhead line 1, the current collector 10, and the after-mentionedreference photographic subjects 24. The camera 21B and the illuminationdevices 23 are connected to an unillustrated power source, andtherefore, power is supplied to the camera 21B and the illuminationdevices 23 by an operator turning on key switches in the cab 8. That is,the camera 21B starts to shoot the overhead line 1, the currentcollector 10, and the after-mentioned reference photographic subjects 24in response to the ON operation of the key switch.

In addition, the illumination device 23 starts the lighting regardlessof day or night with an operation of turning on an illumination switch.The illumination device 23 performs the lighting or non-lighting by anoperator, but, a lighting state of the illumination device 23 may bedetermined in association with a time set by a timer or in accordancewith a luminance average value of an image. According to the presentinvention, it is basically possible to perform the day or nightdetermination regardless of a combination of the lighting state of theillumination device 23 and the day or night of the imaging environment.

Next, an explanation will be made of the reference photographic subjects24 attached on the extension plate 19 of the imaging device attachmenttool 15.

The reference photographic subjects 24 are shot by the camera 21B in theimaging device 21 in the positions different from the overhead line 1and the current collector 10 in the image area to be shot. That is, thereference photographic subjects 24 are arranged to be accommodatedwithin the shooting range H in the positions not to interrupt theshooting of the overhead line 1 and the current collector 10. Thereference photographic subjects 24 are used when an after-mentioned dayor night determination processing section 29 in the controller 26determines day or night. In addition, the reference photographicsubjects 24 are configured of the left reference photographic subject24A disposed in the left side (one side) in the left-right direction,and the right reference photographic subject 24B disposed in the rightside (the other side) in the left-right direction. The left referencephotographic subject 24A corresponds to a first reference photographicsubject of the present invention, and the right reference photographicsubject 24B corresponds to a second reference photographic subject ofthe present invention.

As shown in FIG. 2 and FIG. 3, the left reference photographic subject24A is formed in a plate shape by a metallic material, a resin materialor the like, and extends upward from the left reference photographicsubject fixing part 19B of the imaging device attachment tool 15. Theleft reference photographic subject 24A is configured of a fixing part24A1 fixed to the left reference photographic subject fixing part 19B, abend part 24A2 bending from the top end to the forward side of thefixing part 24A1, and a shot imaging part 24A3 that extends from the tipend to the upward side of the bend part 24A2 and is shot by the camera21B.

A through hole (not shown) is formed in the fixing part 24A1 of the leftreference photographic subject 24A to penetrate in the thicknessdirection. The left reference photographic subject 24A is attached onthe left reference photographic subject fixing part 19B by screwing thebolt 25 through the through hole into the screw seat 19B1 of the leftreference photographic subject fixing part 19B. As shown in FIG. 10 andFIG. 11, the shot imaging part 24A3 is set to be reflected in the leftlower end side of the image to be shot by the camera 21B. In this case,a central area of the shot imaging part 24A3 is formed as a leftreference area 24A4 in which an after-mentioned luminance detectingsection 30 in the controller 26 detects a luminance average value. Theright reference photographic subject 24B also is configured to include afixing part 24B1, a bend part 24B2, a shot imaging part 24B3 and a rightreference area 24B4.

In this way, the left reference photographic subject 24A and the rightreference photographic subject 24B are arranged to be reflected inpositions symmetric about the center of the image in the left-rightdirection. In addition, the shot imaging part 24A3 of the left referencephotographic subject 24A and the shot imaging part 24B3 of the rightreference photographic subject 24B are positioned on the same plane. Asa result, even when disturbance of sunlight or the like is reflected onthe left reference photographic subject 24A to be reflected in theimaging device 21, the sunlight is prevented from being reflected to theright reference photographic subject 24B in a relative positiondifferent from the left reference photographic subject 24A in relationto the imaging device 21 and being reflected in the imaging device 21.

In addition, since these reference photographic subjects 24A, 24B arealways positioned in the same area of the image to be shot because ofbeing fixed integrally with the imaging device 21 through the imagingdevice attachment tool 15, a stable imaging condition can be obtained.Accordingly, the after-mentioned day or night determination processingsection 29 of the controller 26 can perform the determination of day ornight with accuracy by using any luminance average value of theluminance average value of the left reference photographic subject 24Aand the luminance average value of the right reference photographicsubject 24B. An explanation will be later made of the details of thecontrol processing of the day or night determination to be executed bythe day or night determination processing section 29.

FIG. 4 shows a control block diagram of the controller 26. Here, thecontroller 26 is connected to an unillustrated power source and isactivated in response to an ON operation of the key switch. Thecontroller 26 is configured of a microcomputer, for example, andprocesses an image shot by the camera 21B in the imaging device 21. Thecontroller 26 is disposed in the cab 8, for example, and has an inputside to which the imaging device (the camera 21B) is connected via thecable 22 and an output side to which an after-mentioned display device39 and an unillustrated voice output device are connected. Parametersfor image processing and programs of the control processing as shown inFIG. 5 to FIG. 9 are stored in a memory 26A in the controller 26. Inaddition, the controller 26 is configured to include an image inputsection 27, the day or night determination processing section 29, animage processing section 32, an image synthesis processing section 37,and an output section 38.

The image input section 27 takes in an image signal from the imagingdevice 21 to be converted into digital data of eight bits of each ofRGB. The image converted into the digital data has one part that isinputted into the day or night determination processing section 29 andthe other part that is inputted into the image processing section 32.The day or night determination processing section 29 detects a luminancesignal of each of pixels from the image inputted into the luminancedetecting section 30 therein, and, next, performs the day or nightdetermination on the imaging environment in an area comparison section31 based upon luminance information in a detected specific pixel area.The image processing section 32 executes the image processing to theinputted image by switching an image processing parameter, based uponthe result of the day or night determination by the day or nightdetermination processing section 29. The image processing parameter (aday or night determination processing parameter) includes presence orabsence of a lighting luminance threshold value Lon, an extinctionluminance threshold value Loff, a binarization luminance thresholdvalue, and white and black inversion processing, which will be describedlater.

Next, an explanation will be made of the processing on the shot image.The image processing section 32 executes the image processing based uponany mode of a daylight mode and a night mode determined by the result ofthe day or night determination by the day or night determinationprocessing section 29. It should be noted that the controller 26 is setto the daylight mode in an initial stage when the key switch is turnedon.

The image input section 27 receives input of the shot images of theoverhead line 1, the current collector 10 and the reference photographicsubject 24 shot by the camera 21B in the imaging device 21 (convenientlyreferred to as “day image 28D” or “night image 28N” for easilydistinguishing day or night during which the shooting is performed atthe time of exemplifying the shot image in the following explanation).Here, regarding the reference photographic subject 24, since a sky areaS is brighter in the daylight regardless of a lighting state of theillumination device 23, the reference photographic subject 24 isreflected dark in the day image 28D by the AGC function of the camera21B in the imaging device 21 (refer to FIG. 10). Meanwhile, since it isdifficult to distinguish between the overhead line 1, the currentcollector 10 and the reference photographic subject 24 without turningon the illumination device 23 at night, the overhead line 1, the currentcollector 10 and the reference photographic subject 24 are reflectedbrightly in the night image 28N and the sky area S is reflected dark byturning on the illumination device 23 (refer to FIG. 11).

The day or night determination processing section 29 determines day ornight of the day image 28D or the night image 28N inputted into theimage input section 27. Specifically, the day or night determinationprocessing section 29 determines day or night based upon a luminanceaverage value (luminance information) of the reference photographicsubjects 24 of the day image 28D and the night image 28N inputted intothe image input section 27. Therefore, the day or night determinationprocessing section 29 is configured to include the luminance detectingsection 30 and the area comparison section 31.

The luminance detecting section 30 detects a luminance average value ofthe left reference photographic subject 24A and a luminance averagevalue of the right reference photographic subject 24B in the day image28D or the night image 28N inputted into the image input section 27.Specifically, the luminance detecting section 30 detects a leftluminance average value La of the left reference area 24A4 correspondingto the left reference photographic subject 24A in the image and detectsa right luminance average value Lb of the right reference area 24B4corresponding to the right reference photographic subject 24B in theimage.

The left luminance average value La and the right luminance averagevalue Lb each are detected as data of eight bits for expressing 256gradations, for example. Therefore, the left luminance average value Laand the right luminance average value Lb each are detected as anumerical value between 0 and 255 (0≤La, Lb≤255). In this case, as eachnumerical value of the luminance average values La, Lb is larger, eachof the reference areas 24A, 24B is brighter. In addition, the leftluminance average value La and the right luminance average value Lb areoutputted to the area comparison section 31.

The area comparison section 31 determines day or night based upon theleft luminance average value La and the right luminance average value Lboutputted from the luminance detecting section 30. In this case, the dayor night determination processing section 29 compares the left luminanceaverage value La and the right luminance average value Lb with thelighting luminance threshold value Lon stored in the memory 26A todetermine day or night. The lighting luminance threshold value Lon is athreshold value at the time of performing the determination of day ornight in a case where the overhead line 1, the current collector 10 andthe reference photographic subjects 24 are lighted by sunlight or theillumination device 23, and is set by experiments, simulations or thelike based upon an environment in the surrounding area where the dumptruck 2 travels, for example. The area comparison section 31 outputs theresult of the day or night determination toward the binarizationprocessing section 33 and the inversion processing section 34 in theimage processing section 32, which will be described later.

Here, since the sky area S is bright in the day image 28D by the AGCfunction of the camera 21B, the left reference photographic subject 24Aand the right reference photographic subject 24B are relativelyreflected darker. Meanwhile, in the night image 28N the sky area S isdark and the left reference photographic subject 24A and the rightreference photographic subject 24B are illuminated by the illuminationdevice 23 to be reflected brightly. Therefore, the area comparisonsection 31 determines the environment as the daylight when the leftluminance average value La and the right luminance average value Lb eachare equal to or less than the lighting luminance threshold value Lon(for example, equal to or less than 200, that is, La, Lb≤200), anddetermines the environment as the night when the left luminance averagevalue La and the right luminance average value Lb each are larger thanthe lighting luminance threshold value Lon (La, Lb>Lon).

In addition, in the daylight, there are some cases where the sunlight orthe like is reflected on the left reference photographic subject 24A orthe right reference photographic subject 24B during the traveling of thedump truck 2 to temporarily brighten the left reference photographicsubject 24A or the right reference photographic subject 24B. Forexample, in a case where the left luminance average value La of thetemporarily brightened left reference photographic subject 24A is equalto or more than the lighting luminance threshold value Lon, the areacomparison section 31 possibly determines erroneously the environment asthe night regardless of the daylight. Therefore, the area comparisonsection 31 performs the determination of day or night using theluminance average value that is a smaller one of the left luminanceaverage value La and the right luminance average value Lb as adetermination luminance average value L in the daylight mode. Thereby,in a case where the dump truck 2 travels in the daylight, it is possibleto suppress the erroneous determination of day or night caused by thedisturbance reflected in the imaging device 21 by the reflection of thesunlight on any one of the reference photographic subjects 24.

Accordingly, even when the dump truck 2 is traveling, the controller 26can accurately perform the day or night determination using thereference photographic subject 24 in which a luminance change of theimage is smaller. In addition, since the determination of day or nightis performed using the luminance average value that is the smaller oneof the left reference photographic subject 24A and the right referencephotographic subject 24B arranged in symmetrical positions in theleft-right direction about the center of the image as the determinationluminance average value L, it is possible to further improve theaccuracy of the day or night determination.

The image processing section 32 executes different image processing byswitching a parameter (an image processing parameter) in the daylightand at night based upon the result of the day or night determinationdetermined by the day or night determination processing section 29,thereby causing the overhead line 1 and the current collector 10 in theimage to be more easily recognized. In addition, the image processingsection 32 is configured to include the binarization processing section33, the inversion processing section 34, a recognition processingsection 35 and a detection frame generating section 36.

The binarization processing section 33 converts the day image 28Dinputted into the image input section 27 to a white and black image 28D1for day mode in which the sky area S having a typical luminancedistribution in the daylight is bright, and converts the night image 28Ninputted into the image input section 27 to a white and black image 28N1for night mode in which the sky area S having a typical luminancedistribution at night is dark. In this case, as shown in FIG. 10, theday image 28D is converted to the white and black image 28D1 for daymode in which the sky area S is converted to a white color and theoverhead line 1, the current collector 10 and the reference photographicsubjects 24 each are converted to a black color. Meanwhile, as shown inFIG. 11, the night image 28N is converted to the white and black image28N1 for night mode in which the sky area S is converted to a blackcolor and the overhead line 1, the current collector 10 and thereference photographic subjects 24 each are converted to a white color.

Here, as shown in FIG. 4, the determination result from the day or nightdetermination processing section 29 is inputted also into thebinarization processing section 33, and a binarization luminancethreshold value also, which is an image processing parameter forcarrying out appropriate binarization in accordance with a luminancedistribution of an image different between day and night, is changed todiffer between the daylight mode and the night mode, respectively. As aresult, by distinguishing the overhead line 1, the current collector 10and the reference photographic subjects 24 over the sky area S forrecognition, it is possible to obtain a binarization image appropriatefor the image processing to be executed to an image of each of day andnight. The white and black image 28D1 for daylight mode or the white andblack image 28N1 for night mode conversion-processed to the white andblack image in the binarization processing section 33 is outputted intothe inversion processing section 34.

The inversion processing section 34 executes the white and blackinversion processing of the white and black image 28N1 for night mode.Specifically, in a case where the inversion processing section 34recognizes the result of the day or night determination outputted fromthe area comparison section 31 in the day or night determinationprocessing section 29 as the night determination, the image outputtedinto the inversion processing section 34 from the binarizationprocessing section 33 is recognized as the white and black image 28N1for night mode to execute the white and black inversion processing(switch of the parameter) of the white and black image 28N1 for nightmode. Thereby, the white and black image 28N1 for night mode becomes thesame image as the white and black image 28D1 for daylight mode since thesky area S changes from black color to white color and the overhead line1, the current collector 10 and the reference photographic subjects 24become from white color to black color.

Meanwhile, in a case where the inversion processing section 34recognizes the result of the day or night determination outputted fromthe area comparison section 31 in the day or night determinationprocessing section 29 as the day determination, the white and blackinversion processing of the white and black image 28D1 for day modeoutputted into the inversion processing section 34 from the binarizationprocessing section 33 is not executed. That is, in a case where theresult of the day or night determination is recognized as the nightdetermination, the inversion processing section 34 executes the whiteand black inversion processing of the white and black image 28N1 fornight mode such that the sky area S becomes a white color and theoverhead line 1, the current collector 10 and the reference photographicsubjects 24 become a black color, whereby the white and black image 28N1for night mode is unified to the image in the same form as the white andblack image 28D1 for day mode. In addition, the unified white and blackimage 28D1 for day mode is outputted to the recognition processingsection 35.

The recognition processing section 35 recognizes the overhead line 1 andthe current collector 10 from the white and black image 28D1 for daymode outputted from the inversion processing section 34. Specifically,the recognition processing section 35 moves a template image, which isin advance stored in the memory 26A, in the white and black image 28D1for day mode at constant intervals to carry out pattern matching forlooking for a place the highest in a correlative value, thus recognizingthe overhead line 1 and the current collector 10.

In this case, since the white and black image 28N1 for night mode isconverted to the white and black image 28D1 for day mode in theinversion processing section 34, the recognition processing section 35can carry out the pattern matching by one kind of template image matchedto the white and black image 28D1 for day mode through the day and thenight. Thereby, a processing speed for recognizing the overhead line 1and the current collector 10 becomes faster than in a case of carryingout the pattern matching using two kinds of template images composed ofa template image for day and a template image for night. Further, it ispossible to reduce a load of the calculation processing associated withthe pattern matching.

The detection frame generating section 36 generates a straight line anda detection frame to a position of each of the overhead line 1 and thecurrent collector 10 recognized in the recognition processing section35. That is, the detection frame generating section 36 generates thestraight line in the position of being recognized as the overhead line 1in the recognition processing section 35 and generates the detectionframe in the position of being recognized as the current collector 10 inthe recognition processing section 35, which are outputted to the imagesynthesis processing section 37.

The image synthesis processing section 37 synthesizes the straight lineof the overhead line 1 and the detection frame of the current collector10 that are generated in the detection frame generating section 36 withthe colored day image 28D or the colored night image 28N inputted intothe image input section 27. In addition, the synthesized image isoutputted to the after-mentioned display device 39 from an outputsection 38. In addition, in the output section 38, an unillustratedmonitor part in the controller 26 performs output of warning soundgeneration to an unillustrated warning sound generating device in a casewhere the current collector 10 is about to come off from the overheadline 1, for example.

The display device 39 displays the image processed by the controller 26.The display device 39 is disposed in the cab 8, for example, and can beoperated and confirmed in a state where an operator is seated on anoperator's seat. As shown in FIG. 12 and FIG. 13, the display device 39is configured to include a key switch 40, an illumination switch 41 anda display part 42. When an operator performs an ON operation of the keyswitch 40, the image processed by the controller 26 is displayed on thedisplay part 42.

Here, as shown in FIG. 12, in the daylight an image in which a straightline 43 of the overhead line 1 and a detection frame 44 of the currentcollector 10 are processed to be synthesized in the image synthesisprocessing section 37 is displayed on the day image 28D. The straightline 43 shown in a dashed-dotted line in FIG. 12 highlights the overheadline 1 in a red, blue or yellow color, for example. Meanwhile, thedetection frame 44 shown in a dotted line in FIG. 12 highlights thecurrent collector 10 in a color different from that of the straight line43, for example. In addition, as shown in FIG. 13, as similar even atnight, the overhead line 1 is highlighted by the straight line 43 andthe current collector 10 is highlighted by the detection frame 44. As aresult, a position of the current collector 10 to the overhead line 1 iseasily recognized, making it possible to improve the operability indriving control of the dump truck 2.

The monitor device 11 mounted on the dump truck 2 according to the firstembodiment has the configuration as described above, and next, anexplanation will be made of the control processing by the controller 26in the monitor device 11 with reference to FIG. 5 to FIG. 9. It shouldbe noted that the control processing of the controller 26 is repeatedlyexecuted in a predetermined control cycle until the key switch is turnedoff after the key switch is turned on, for example. That is, the day ornight determination, the mode setting, and the image processing basedupon the set mode are repeatedly executed.

First, as shown in FIG. 5, the controller 26 performs an initial settingof variable when the processing operation is started by turning on thekey switch. In addition, in step 1, the daylight mode is set for a caseof performing the day or night determination for the first time (afterturning on the key switch) (Result=Daylight mode).

Next, as shown in FIG. 6, the controller 26 determines whether toexecute the control processing of the day or night determination in thedaylight mode or the control processing of the day or nightdetermination in the night mode. In this case, in step 11, it isdetermined whether or not a mode set (stored) at present is the daylightmode (Result=Daylight mode?). That is, in a case after the key switch isturned on, the image processing parameter for daylight mode is outputtedfrom the memory 26A in the controller 26 in step 1. Meanwhile, in a caseother than that, an image processing parameter for mode based upon theprevious result of the day or night determination is outputted from thememory 26A in the controller 26.

In addition, in a case where in step 11 “YES” is determined, that is,the daylight mode is set, the process goes to step 12, wherein thecontrol processing of the day or night determination in the daylightmode is executed. Meanwhile, in a case where in step 11 “NO” isdetermined, that is, the night mode is set, the process goes to step 13,wherein the control processing of the day or night determination in thenight mode is executed.

Next, an explanation will be made of the control processing of the dayor night determination in the daylight mode that is executed in step 12in FIG. 6 with reference to FIG. 7. The control processing of the day ornight determination in the daylight mode is executed in the day or nightdetermination processing section 29 in the controller 26.

First, in step 21, the left luminance average value La in the leftreference area 24A4 of the left reference photographic subject 24A isobtained. That is, the luminance detecting section 30 in the day ornight determination processing section 29 obtains the left luminanceaverage value La in the left reference area 24A4 of the image (the dayimage 28D or the night image 28N) inputted into the image input section27. In next step 22, the right luminance average value Lb in the rightreference area 24B4 of the right reference photographic subject 24B isobtained. That is, the luminance detecting section 30 in the day ornight determination processing section 29 obtains the right luminanceaverage value Lb in the right reference area 24B4 of the image (the dayimage 28D or the night image 28N) inputted into the image input section27. The left luminance average value La and the right luminance averagevalue Lb each are set as a value between 0 and 255 in such a manner asto be the larger as the left reference photographic subject 24A and theright reference photographic subject 24B are brighter (0≤La, Lb≤255).

In next step 23, it is determined whether the left luminance averagevalue La is equal to or more than the right luminance average value Lb(La≥Lb). That is, the area comparison section 31 in the day or nightdetermination processing section 29 determines which of the leftluminance average value La and the right luminance average value Lb is aluminance average value that is a smaller one thereof. In a case wherein step 23 “YES” is determined, that is, the left luminance averagevalue La is equal to or more than and the right luminance average valueLb, the process goes to step 24, wherein the determination luminanceaverage value L is set to the right luminance average value Lb(L=La≤Lb). Meanwhile, in a case where in step 23 “NO” is determined,that is, the left luminance average value La is determined to be smallerthan the right luminance average value Lb, the process goes to step 25,wherein the determination luminance average value L is set to the leftluminance average value La (L=La<Lb).

As a result, disturbance of sunlight or the like is reflected in thedaylight to brighten any one of the left reference photographic subject24A and the right reference photographic subject 24B, thus making itpossible to exclude the luminance average value that has temporarilybecome a large value. Accordingly, the erroneous determination of thearea comparison section 31 can be suppressed to improve thedetermination accuracy of the day or night determination.

In next step 26, it is determined whether the determination luminanceaverage value L is equal to or less than the lighting luminancethreshold value Lon (Lon≥L). That is, the area comparison section 31 inthe day or night determination processing section 29 determines whetheror not the luminance average value as the smaller value of the leftluminance average value La and the right luminance average value Lb isequal to or less than Lon. In a case where in step 26 “YES” isdetermined, that is, the determination luminance average value L isdetermined to be equal to or less than the lighting luminance thresholdvalue Lon, the process goes to step 27. Meanwhile, in a case where instep 26 “NO” is determined, that is, the determination luminance averagevalue L is determined to be larger than the lighting luminance thresholdvalue Lon, the process goes to step 28.

In step 27, the daylight mode is set (Result=Daylight mode). That is,the area comparison section 31 sets the daylight mode to the imageprocessing section 32 in the controller 26 based upon the image inputtedinto the image input section 27 being determined as the day image 28D,and the process ends.

Meanwhile, in step 28, the night mode is set (Result=Night mode). Thatis, the area comparison section 31 sets the night mode to the imageprocessing section 32 in the controller 26 based upon the image inputtedinto the image input section 27 being determined as the night image 28N,and the process ends.

Next, an explanation will be made of the control processing of the dayor night determination in the night mode that is executed in step 13 inFIG. 6 with reference to FIG. 8. The control processing of the day ornight determination is executed in the day or night determinationprocessing section 29 in the controller 26.

First, in step 31, the left luminance average value La in the leftreference area 24A4 of the left reference photographic subject 24A isobtained. In step 31, the control processing as similar to that in step21 in FIG. 7 is executed. It should be noted that in step 31, the rightluminance average value Lb in the right reference area 24B4 of the rightreference photographic subject 24B may be obtained instead of obtainingthe left luminance average value La, and the subsequent controlprocessing may be executed using the right luminance average value Lb.That is, there is assumed that at night, the luminance level of thereference photographic subject 24 gets high because of the reflection ofthe optical source of a street lamp or the like on the referencephotographic subject 24. However, since at night, the referencephotographic subject 24 is illuminated by the illumination device 23 tostay high in the luminance level, even when the disturbance of thestreet lamp or the like is reflected on the reference photographicsubject 24, the day or night determination is not affected. Accordingly,in the night mode a luminance average value as any one of the leftluminance average value La of the left reference photographic subject24A and the right luminance average value Lb of the right referencephotographic subject 24B is obtained.

In next step 32 it is determined whether or not the left luminanceaverage value La is equal to or less than the lighting luminancethreshold value Lon (Lon≥La). That is, it is determined whether or notthe left luminance average value La is equal to or less than thelighting luminance threshold value Lon by setting the left luminanceaverage value La as the determination luminance average value L. In acase where in step 32 “YES” is determined, that is, the left luminanceaverage value La is determined to be equal to or less than the lightingluminance threshold value Lon, the process goes to step 33, wherein thedaylight mode is set (Result=Daylight mode), and process ends.Meanwhile, in a case where in step 32 “NO” is determined, that is, theleft luminance average value La is larger than the lighting luminancethreshold value Lon, the process goes to step 34, wherein the night modeis set (Result=Night mode), and process ends.

Next, an explanation will be made of the recognition control processingto the overhead line 1 and the current collector 10 to be executed inthe image processing section 32 in the controller 26 with reference toFIG. 9.

First, in step 41, the white and black binarization processing of animage is executed. The white and black binarization processing of theimage is executed in the binarization processing section 33 in the imageprocessing section 32. As shown in FIG. 10, the white and blackbinarization processing of the image converts the colored day image 28Dinputted into the image input section 27 to the white and black image28D1 for day mode. Meanwhile, as shown in FIG. 11, the white and blackbinarization processing of the image converts the colored night image28N inputted into the image input section 27 to the white and blackimage 28N1 for night mode.

In next step 42, it is determined whether or not the result of the dayor night determination is the daylight mode (Result=Daylight mode). Theday or night determination is performed in the area comparison section31 in the day or night determination processing section 29, and thedetermination result is outputted to the inversion processing section 34in the image processing section 32. In addition, in a case where in step42 “YES” is determined, that is, the result of the day or nightdetermination is determined as the daylight mode, the process goes tostep 44. Meanwhile, in a case where in step 42 “NO” is determined, thatis, the result of the day or night determination is determined as thenight mode, the process goes to step 43.

In step 43, the white and black inversion processing is executed. Thewhite and black inversion processing is executed in the inversionprocessing section 34 in the image processing section 32. That is, in acase where the result determined in the area comparison section 31 is atnight, the inversion processing section 34 executes the white and blackinversion processing of the white and black image 28N1 for night modewhite and black-converted in the binarization processing section 33.Thereby, in the white and black image 28N1 for night mode, the sky areaS changes from black color to white color and the overhead line 1, thecurrent collector 10 and the reference photographic subjects 24 areconverted from white color to black color (refer to FIG. 11). Thereby,the white and black image 28N1 for night mode becomes an image in thesame form as the white and black image 28D1 for daylight mode, and thisimage is outputted to the recognition processing section 35.

In next step 44, the recognition processing of the current collector andthe overhead line is executed. This recognition processing is executedin the recognition processing section 35 in the image processing section32. In the recognition processing section 35, the template image, whichis in advance stored in the memory 26A in the controller 26, is moved atconstant intervals in the image (the white and black image 28D1 for daymode) outputted from the inversion processing section 34 to executepattern matching for looking for a place the highest in a correlativevalue, thus recognizing the overhead line 1 and the current collector10, and the process ends.

Next, FIG. 14 and FIG. 15 show a second embodiment of the presentinvention. The second embodiment is characterized by control processingof a day or night determination in a case where the illumination device23 as shown in the first embodiment is not disposed or in a case wherethe illumination device 23 is turned off. It should be noted that in thesecond embodiment, components identical to those in the first embodimentare referred to as identical reference numerals, and the explanation isomitted.

An explanation on a series of the processing as shown in FIG. 5 and FIG.6 in the same way as the first embodiment is omitted, and next, anexplanation will be made of the control processing of the day or nightdetermination in the daylight mode that is executed in step 12 in FIG. 6with reference to FIG. 14. This control processing of the day or nightdetermination is executed in the day or night determination processingsection 29 in the controller 26.

In step 51, the left luminance average value La in the left referencearea 24A4 of the left reference photographic subject 24A is obtained. Instep 51, the control processing as similar to that in step 21 in FIG. 7is executed. It should be noted that in step 51, instead of obtainingthe left luminance average value La, the right luminance average valueLb in the right reference area 24B4 of the right reference photographicsubject 24B may be obtained to execute the subsequent control processingusing the right luminance average value Lb. The left luminance averagevalue La and the right luminance average value Lb each are set as avalue between 0 and 255 in such a manner as to be the larger as the leftreference photographic subject 24A and the right reference photographicsubject 24B are brighter (0≤La, Lb≤255). In this case, withoutillumination (without irradiation), the left luminance average value Laand the right luminance average value Lb each become a smaller valuethan with illumination (in the first embodiment).

In next step 52, it is determined whether or not the left luminanceaverage value La is equal to or more than the extinction luminancethreshold value Loff (Loff≤La). That is, the left luminance averagevalue La is set as the determination luminance average value L todetermine whether or not the left luminance average value La is equal toor more than the extinction luminance threshold value Loff. Theextinction luminance threshold value Loff is a threshold value at thetime of performing the determination of day or night in a case where theoverhead line 1, the current collector 10 and the reference photographicsubjects 24 are not illuminated, and is a value smaller than thelighting luminance threshold value Lon. In addition, the extinctionluminance threshold value Loff also is in advance stored in the memory26A in the controller 26. That is, the left luminance average value Laand the right luminance average value Lb each are a value equal to ormore than Loff in the daylight and the value gradually becomes smalleras closer to the night.

Here, in the daylight, the luminance average value of the referencephotographic subject 24 is higher (larger) than at night. In this case,for example, when the dump truck 2 enters the shade at the traveling,the luminance average value of the reference photographic subject 24becomes low, therefore, possibly causing the day or night determinationto be an erroneous determination. Therefore, the extinction luminancethreshold value Loff is set by experiments, simulations or the like insuch a manner as to be larger than the luminance average value of thereference photographic subject 24 to be detected at night and smallerthan the luminance average value of the reference photographic subject24 to be detected in a case where the dump truck 2 enters the shade.Accordingly, in a case of the day or night determination in the daylightmode, it is possible to perform the day or night determination basedupon the luminance average value of the reference photographic subjectthat is any one of the left reference photographic subject 24A and theright reference photographic subject 24B without consideration of theerroneous determination of the day or night determination caused by thedisturbance.

In a case where in step 52 “YES” is determined, that is, the leftluminance average value La is determined to be equal to or more than theextinction luminance threshold value Loff, the process goes to step 53,wherein the result of the day or night determination is set to thedaylight mode (Result=Daylight mode), and the process ends. Meanwhile,in a case where in step 52 “NO” is determined, that is, the leftluminance average value La is determined to be a value smaller than theextinction luminance threshold value Loff, the process goes to step 54,wherein the result of the day or night determination is set to the nightmode (Result=Night mode), and the process ends.

Next, an explanation will be made of the control processing of the dayor night determination in the night mode that is executed in step 13 inFIG. 6 with reference to FIG. 15. The control processing of the day ornight determination is executed in the day or night determinationprocessing section 29 in the controller 26.

In step 61 to step 65, control processing in the same way as that fromstep 21 to step 25 in FIG. 7 is executed. In this case, in step 63, itis determined whether or not the left luminance average value La isequal to or more than the right luminance average value Lb (La Lb). As aresult, an optical source (disturbance) of a street lamp or the like isreflected at night to brighten any one of the left referencephotographic subject 24A and the right reference photographic subject24B, thus making it possible to exclude the luminance average value thathas temporarily become a large value. Accordingly, the erroneousdetermination of the day or night determination processing section 29can be suppressed to improve the determination accuracy of the day ornight determination.

In step 66, it is determined whether or not the determination luminanceaverage value L is equal to or more than the extinction luminancethreshold value Loff (for example, 75) (Loff≤L). That is, the areacomparison section 31 in the day or night determination processingsection 29 determines whether or not the luminance average value as asmaller value of the left luminance average value La and the rightluminance average value Lb is equal to or more than Loff. In a casewhere in step 66 “YES” is determined, that is, the determinationluminance average value L is determined to be equal to or more than theextinction luminance threshold value Loff, the process goes to step 67,wherein the result of the day or night determination is set to thedaylight mode (Result=Daylight mode), and the process ends. Meanwhile,in a case where in step 66 “NO” is determined, that is, thedetermination luminance average value L is determined to be a valuesmaller than the extinction luminance threshold value Loff, the processgoes to step 68, wherein the result of the day or night determination isset to the night mode (Result=Night mode), and the process ends.

In this way, the second embodiment also can, in the same way as thefirst embodiment, perform the determination of day or night withaccuracy based upon the luminance average value of the referencephotographic subjects 24 to be reflected in the positions not tointerrupt the shooting of the objects (the overhead line 1 and thecurrent collector 10). In addition, since the left referencephotographic subject 24A and the right reference photographic subject24B as the reference photographic subjects 24 are arranged to bedisplayed in the different positions in the image, it is possible tosuppress the erroneous determination of the day or night determinationby performing the determination of day or night based upon the smallerluminance average value at night.

Next, FIG. 16 and FIG. 18 show a third embodiment of the presentinvention. The third embodiment is characterized in that the controller26 is provided with an illumination determination section 51 configuredto determine whether the illumination device 23 is turned on or turnedoff and the control processing of the day or night determination isexecuted based upon the determination result of the illuminationdetermination section 51. It should be noted that in the thirdembodiment, components identical to those in the first embodiment arereferred to as identical reference numerals, and the explanation isomitted.

The illumination determination section 51 is configured to determine thelighting and the extinction of the illumination device 23 and isdisposed in the controller 26. The illumination determination section 51has an input side that is connected to the illumination device 23 and anoutput side that is connected to the area comparison section 31 in theday or night determination processing section 29. The illuminationdetermination section 51 can determine the lighting and the extinctionof the illumination device 23 based upon information of ON and OFFoperations of the illumination device obtained from, for example, alighting sensor (not shown) for detecting the lighting and theextinction of the illumination device 23, a voltage (current) sensor(not shown) for detecting power supply to the illumination device 23, anillumination switch 41 for performing the ON and OFF operations of theillumination device 23 disposed in the cab 8, and the like.

Next, an explanation will be made of the control processing of the dayor night determination that is executed in the controller 26.

An explanation on a series of the processing as shown in FIG. 5 and FIG.6 in the same way as the first embodiment is omitted, and next, anexplanation will be made of the control processing of the day or nightdetermination that is executed in the controller 26 based upon thedetermination result of the lighting and the extinction of theillumination device 23 with reference to FIG. 17. This controlprocessing as shown in FIG. 17 is stored in the memory 26A in thecontroller 26.

First, in step 71 the information of the ON and OFF operations of theillumination device 23 is obtained by the illumination determinationsection 51 in the controller 26, and the process goes to next step 72.In step 72, it is determined whether or not the illumination device 23is turned on. In addition, in a case where in step 72 “YES” isdetermined, that is, the illumination device 23 is determined to beturned on, the process goes to step 73. Meanwhile, in a case where instep 72 “NO” is determined, that is, the illumination device 23 isdetermined to be turned off, the process goes to step 76.

In step 73, it is determined whether or not the mode set at present isthe daylight mode (Result=Daylight mode). That is, in a case after thekey switch is turned on, the daylight mode is set to the memory 26A inthe controller 26 in step 1 in FIG. 5. Meanwhile, in a case other thanthat, a mode based upon the previous result of the day or nightdetermination is set to the memory 26A in the controller 26. Inaddition, in a case where in step 73 “YES” is determined, that is, thedaylight mode is set, the process goes to step 74, wherein the controlprocessing of the day or night determination in the daylight mode asshown in FIG. 7 is executed, and the process ends. Meanwhile, in a casewhere in step 73 “NO” is determined, that is, the night mode is set, theprocess goes to step 75, wherein the control processing of the day ornight determination in the night mode as shown in FIG. 8 is executed,and the process ends.

In step 76, likewise, it is determined whether or not the mode set atpresent is the daylight mode (Result=Daylight mode). In addition, in acase where in step 76 “YES” is determined, that is, the daylight mode isset, the process goes to step 77, wherein the control processing of theday or night determination in the daylight mode as shown in FIG. 14 isexecuted, and the process ends. Meanwhile, in a case where in step 76“NO” is determined, that is, the night mode is set, the process goes tostep 78, wherein the control processing of the day or nightdetermination in the night mode as shown in FIG. 15 is executed, and theprocess ends.

As a result, the third embodiment can likewise achieve the operation andthe effect as similar to those in the first embodiment. Particularly, itis detected whether or not the illumination device 23 is illuminatingthe overhead line 1, the current collector 10 and the referencephotographic subjects 24 regardless of the daylight or the night, andthe luminance threshold value of the day or night determination ischanged to the lighting luminance threshold value Lon and the extinctionluminance threshold value Loff based upon the detection result.Therefore, the day or night determination can be performed in accordancewith the situation.

It should be noted that in the aforementioned first embodiment, a casewhere the shot imaging part 24A3 of the left reference photographicsubject 24A and the shot imaging part 24B3 of the right referencephotographic subject 24B are arranged on the same plane to be spaced inthe left-right direction is explained. However, the present invention isnot limited thereto, but, for example, as in the case of a firstmodification example as shown in FIG. 18, a shot image part 62A of aleft reference photographic subject 62 and a shot image part 63A of aright reference photographic subject 63 may be arranged to form an angletherebetween by bending a left reference photographic subject fixingpart 61A and a right reference photographic subject fixing part 61B inan extension plate 61 of the bracket 12. In this case, the angle betweenthe left reference photographic subject 62 and the right referencephotographic subject 63 is set such that the disturbance of the sunlightor the like is not reflected on the shot image part 62A and the shotimage part 63A simultaneously. Reference photographic subjects 64 areconfigured of the left reference photographic subject 62 and the rightreference photographic subject 63.

In addition, in the aforementioned first embodiment, a case where theleft reference photographic subject 24A and the right referencephotographic subject 24B are arranged such that the referencephotographic subjects 24 are reflected on both sides in the image in theleft-right direction, is explained. However, the present invention isnot limited thereto, but, for example, as in the case of a secondmodification example as shown in FIG. 19, reference photographicsubjects 71 composed of a left reference photographic subject 71A and aright reference photographic subject 71B that are formed integrally andare adjusted in an angle there between such that disturbance of thesunlight or the like is not reflected simultaneously thereon may bearranged on either side in the left-right direction to be shot inpositions different from an object in the image area to be shot. In thiscase, the left reference photographic subject 71A and the rightreference photographic subject 71B are formed in a bent state in such amanner as to face the camera 21B in the imaging device 21 at differentangles.

In addition, as in the case of a third modification example as shown inFIG. 20, reference photographic subjects 81 composed of an upperreference photographic subject 81A (a first reference photographicsubject) and a lower reference photographic subject 81B (a secondreference photographic subject) adjusted in an angle in the upper-lowerdirection there between such that disturbance of the sunlight or thelike is not reflected simultaneously thereon may be arranged on eitherside in the left-right direction to be shot in positions different froman object in the image area to be shot. In this case, the upperreference photographic subject 81A is inclined toward the left side inthe left-right direction, for example, and the lower referencephotographic subject 81B is inclined toward the right side in theleft-right direction, for example.

In addition, in the aforementioned first embodiment, as shown in FIG. 8,a case where the day or night determination is performed based upon theluminance average value of any reference photographic subject of theleft reference photographic subject 24A and the right referencephotographic subject 24B in the night mode is explained as an example.However, the present invention is not limited thereto, but, for example,the control processing of the day or night determination in the same wayas the daylight mode as shown in FIG. 7 may be executed even in thenight mode.

That is, the day or night determination may be made based upon theluminance average value as the smaller value of the left luminanceaverage value La and the right luminance average value Lb even in thenight mode. Thereby, since the control processing of the day or nightdetermination can be unified to the control processing as shown in FIG.7 regardless of the previous result (mode) of the day or nightdetermination, it is possible to simplify the control processing of theday or night determination. This can be likewise applied to the daylightmode as shown in FIG. 14 in the second embodiment. Further, this can belikewise applied to the third embodiment.

In addition, in the aforementioned first embodiment, a case of executingthe white and black inversion processing to the white and black image28N1 for night mode in a case where the result of the day or nightdetermination is determined as night is explained. However, the presentinvention is not limited thereto, but, for example, the white and blackinversion processing may be executed to the white and black image 28D1for daylight mode in a case where the result of the day or nightdetermination is determined as the daylight. This can be likewiseapplied to the second embodiment and the third embodiment.

In addition, in the aforementioned first embodiment, a case where thetwo reference photographic subjects 24 composed of the left referencephotographic subject 24A (the first reference photographic subject) andthe right reference photographic subject 24B (the second referencephotographic subject) are disposed is explained as an example. However,the present invention is not limited thereto, but, for example, three ormore reference photographic subjects may be disposed. In a case ofdisposing the three or more reference photographic subjects, theluminance information (the luminance average value) as the smallestvalue, that is, a reference photographic subject having the smallestluminance average value of the plurality of reference photographicsubjects is selected, making it possible to perform the determination ofday or night. This can be likewise applied to the second embodiment andthe third embodiment.

In addition, in the aforementioned embodiments, a case where the monitordevice 11 is mounted on the dump truck 2 to monitor the overhead line 1and the current collector 10 for driving the dump truck 2 is explainedas an example. However, the present invention is not limited thereto,but besides, the monitor device 11 can be used widely as a monitordevice that monitors objects outdoors.

DESCRIPTION OF REFERENCE NUMERALS

-   1: Overhead line (Object)-   2: Dump truck (Vehicle)-   3: Vehicle body-   9: Pantograph-   10: Current collector (Object)-   11: Monitor device-   21: Imaging device-   23: Illumination device-   24, 64, 71, 81: Reference photographic subject-   24A, 62, 71A: Left reference photographic subject (First reference    photographic subject)-   24B, 63, 71B: Right reference photographic subject (Second reference    photographic subject)-   26: Controller-   27: Image input section-   28D: Day image-   28N: Night image-   29: Day or night determination processing section-   32: Image processing section-   51: Illumination determination section-   81A: Upper reference photographic subject (First reference    photographic subject)-   81B: Lower reference photographic subject (Second reference    photographic subject)-   Lon: Lighting luminance threshold value-   Loff: Extinction luminance threshold value

1. A monitor device comprising: an imaging device that is mounted on avehicle and shoots an object outside of the vehicle; a controller thatprocesses an image shot by the imaging device; and a plurality ofreference photographic subjects that are disposed to be fixed integrallywith the imaging device and are shot by the imaging device in positionsdifferent from the object in an image area to be shot, characterized inthat: wherein the controller includes: a day or night determinationprocessing section that determines day or night in an imagingenvironment of the object; and an image processing section that switchesan image processing parameter for recognizing the object in the image byexecuting image processing different in the daylight and at night basedupon the result of the day or night determination determined by the dayor night determination processing section, wherein the day or nightdetermination processing section in the controller performs thedetermination of day or night based upon luminance information of theplurality of reference photographic subjects, and the image processingsection in the controller executes the image processing using the imageprocessing parameter different in the daylight and at night based uponthe result of the day or night determination of the day or nightdetermination processing section.
 2. The monitor device according toclaim 1, wherein the day or night determination processing section inthe controller selects a smallest luminance average value of theplurality of reference photographic subjects disposed to be respectivelydisplayed in different positions in the image shot by the imagingdevice, and performs the determination of day or night of the imagingenvironment by comparing this selected smallest luminance average valuewith a predetermined luminance threshold value.
 3. The monitor deviceaccording to claim 1, further comprising: an illumination device thatilluminates the object and the plurality of reference photographicsubjects that are shot by the imaging device.
 4. The monitor deviceaccording to claim 3, wherein the controller includes an illuminationdetermination section that determines lighting and extinction of theillumination device, and the day or night determination processingsection in the controller performs the determination of day or nightbased upon a lighting luminance threshold value in a case where thedetermination result of the illumination determination section is thelighting, and performs the determination of day or night based upon anextinction luminance threshold value of a smaller value than thelighting luminance threshold value in a case where the determinationresult of the illumination determination section is the extinction. 5.The monitor device according to claim 1, wherein the controller furtherincludes an inversion processing section that inversion-outputsluminance of an image to be inputted in a case where the day or nightdetermination processing section determines the imaging environment asnight.
 6. The monitor device according to claim 1, wherein the objectincludes an overhead line stretched on a traveling path of the vehicle,and a current collector that makes sliding contact with the overheadline to take in power for driving the vehicle, and the imaging device ismounted on the vehicle to be provided with a camera that shoots theoverhead line and the current collector to be included within an imagingrange.
 7. A trolley type vehicle comprising: a vehicle body; apantograph that is disposed in the vehicle body and is capable of movingup and down; and a current collector that makes sliding contact with anoverhead line stretched to face the pantograph to take in power, whereinthe vehicle body being provided with a monitor device including: animaging device that shoots the overhead line and the current collector;and a controller that processes an image shot by the imaging device, andthe controller including: a day or night determination processingsection that determines day or night of an imaging environment of theoverhead line and the current collector shot by the imaging device; andan image processing section that switches an image processing parameterfor recognizing the overhead line and the current collector in the imageby executing image processing different in the daylight and at nightbased upon the result of the day or night determination determined bythe day or night determination processing section, characterized inthat: the vehicle body is provided with a plurality of referencephotographic subjects to be shot by the imaging device in positionsdifferent from the overhead line and the current collector in an imagearea to be shot; the day or night determination processing section inthe controller performs determination of day or night based uponluminance information of the plurality of reference photographicsubjects; and the image processing section in the controller executesthe image processing using the image processing parameter different inthe daylight and at night based upon the result of the day or nightdetermination of the day or night determination processing section.